1. Field of the Invention
The present invention relates to a centrifugal compressor including a main chamber within which an impeller for compressing a gas is provided and a head chamber within which various kinds of auxiliary passageways are provided, the head chamber being mounted to the main chamber.
2. Description of the Prior Art
At first, description will be made of the above-described type of centrifugal compressor of the prior art, with reference to FIGS. 4 and 5. In FIG. 4, reference numeral (1) designates a final stage impeller, numeral (2) designates a delivery port, impellers including the above-mentioned final stage impeller (1) and the above-mentioned delivery port (2) are provided within a main chamber (7), and a gas pressurized by the aforementioned final stage impeller (1) is supplied to the exterior through the delivery port (2). In addition, reference numeral (3) designates a shaft sealing device, numeral (4) designates bearings, numeral (5) designates a head chamber, reference character (A) designates a balance piston chamber, reference character (A1) designates a gas lead-out passageway through which gas within the balance piston chamber (A) passes to the exterior in order to make a pressure within the balance piston chamber (A) balance with a suction pressure of the compressor, reference character (B) designates a leakage gas chamber, reference character (B1) designates a leakage gas passageway through which the leakage gas within the leakage gas chamber (B) passes to the exterior, reference character (C) designates an exhaust oil chamber, reference character (C1) designates a shaft sealing oil discharge passageway through which a shaft sealing oil within the exhaust oil chamber (C) is discharged to the exterior, reference character (D1) designates a passageway through which lead wires for monitoring instruments extend, reference character (E1) designates a shaft sealing oil feed passageway through which shaft sealing oil is fed to the shaft sealing device (3), reference character (E2) designates a shaft sealing oil discharge passageway through which a shaft sealing oil from the shaft sealing device (3) passes to the exterior, reference character (F1) designates a lubricant oil feed passageway for feeding a lubricant oil to the bearings (4), reference character (F2) designates a lubricant oil discharge passageway through which lubricant oil from the bearings (4) passes to the exterior, reference numeral (11) designates a shaft joint, and the above-mentioned shaft sealing device (3), the above-mentioned bearings (4) and the above-mentioned various kinds of auxiliary passageways (A1), (B1), (C1), (D1), (E1), (E2), (F1) and (F2) are provided within the above-described head chamber (5), which is in turn mounted to the above-described main chamber (7) by means of bolts (6). Furthermore, as shown in FIGS. 4 and 5, external piping communicating with the above-mentioned various auxiliary passageways (A1), (B1), (C1), (D1), (E1), (E2), (F1) and (F2), are mounted to an end surface of the above-described head chamber (5) via flanges (8).
FIG. 6 shows another example of the structure in the prior art, in which one end of a piping (9') is welded to an end surface of a head chamber (5), and a flange (10) of an external piping (9) is mounted to a flange (10') provided at the other end of the piping (9').
In the heretofore known centrifugal compressor shown in FIGS. 4 and 5, there are the following shortcomings:
(1) A large number of external piping has to be mounted via the flanges (8) to the end surface of the head chamber (5) having a limited area, hence it is necessary to reduce a pipe diameter of the external pipings, and so, a pressure loss is increased.
(2) Upon assembly and disassembly, it is necessary to attach and detach the flanges (8) with a narrow working space, and so, a workability was very poor. Also, in the case of the centrifugal compressor in the prior art illustrated in FIG. 6, there is a shortcoming in that since the piping (9') is bent, the dimension of the centrifugal compressor in the axial direction must be large, and so, the length in the axial direction of the portion of the shaft joint (11) is elongated.
(3) FIGS. 7(a) and 7(b) show a compressor train comprising one steam turbine and two centrifugal compressors according to the prior art. During the overhaul and inspection work of the compressor in such a compressor train, it is inevitably required to hang up the main and head chamber assembly and to move the same to another place. In such a movement, while the afore-mentioned various piping are disconnected at the flange (8) and piping (9), such disconnection must be carried out in the narrow space between the chamber assembly and the adjacent chamber assembly, thereby making workability very poor. In addition, since a part of the flanged ends of the piping after disconnection dangles in the air without any support, it is dangerous in many cases, and, as a counter-measure thereto, a flanged joint (2) is added in the vicinity of the bed plate of the external piping. Therefore, the above-mentioned disconnection work further includes the work to disconnect the joint (20) to remove the pipe, all of which takes a considerable amount of time.